Annuloplasty (e.g. mitral or tricuspid annuloplasty) is the implantation of an annuloplasty ring (e.g., mitral ring or tricuspid ring) to deform and/or reinforce the valve annulus to correct incompetent valve function. During a classical annuloplasty procedure, the surgeon sizes the valve annulus and chooses a fixed size annuloplasty ring accordingly. This procedure is performed on the arrested heart under cardiopulmonary bypass. However, the effectiveness of a fixed-size annuloplasty ring cannot be assessed during the procedure, because the heart is arrested. Only upon restarting the heart is it possible to assess whether the ring has had the desired effect to correct valve function. If the repair has not been successful, the patient has to undergo a second operation. Without the second operation, there remain certain possible long term consequences of a certain level of residual regurgitation. A further limitation of the classical procedure is that, after implantation of an annuloplasty ring, the size and geometry of the heart and the treated valve annulus may vary over time. Also for example, a dilated heart may respond to corrected valve function by returning to normal size. A fixed-size annuloplasty ring may, over time, become ineffective or inappropriate for the size of the valve annulus. causing recurrent mitral regurgitation and poor clinical outcome. The common practice is to implant too small rings in order to overcome the risk of residual regurgitation. Too small rings result in other problems such as too little blood flow through the mitral valve called mitral stenosis.
Adjustable annuloplasty rings that may be adjusted after implantation in the body have been proposed. By way of example, WO 2012/084714 proposes a partly adjustable annuloplasty ring system able to achieve limited control of an effective shape of the ring. The annuloplasty ring is an assembly comprising an external support ring, an inner adjustable ring, a permanent pressing element mounted between the external and inner rings, and actuating means designed to slide the pressing element around a circumference between the inner and outer rings. The assembly is adjustable by controlling the actuator means to move the pressing element to a desired position around the circumference, in such a way that a specific part of the inner ring at that position is deformed inwardly. An advantage of the assembly using external and inner rings is said to be that the adjustment can be performed without reducing a perimeter length of the inner ring, thereby reducing risk of valve stenosis.
In addition to above issues, a yet further complication that may occur following mitral valve repair and implantation of a mitral ring, is the problem of systolic anterior motion (SAM) in which the anterior mitral valve leaflet deflects towards the septum. SAM can be a cause of potentially life-threatening left ventricular outflow tract obstruction (LVOTO). There are several theories about possible causes of SAM, including possible influence of mitral valve rings on the mitral valve anatomy. When medical treatment is unable to correct it, re-intervention is necessary to correct SAM.